The race is on to build out next-generation mobile wireless 5G networks in the U.S. and, for that matter, around the globe. Of course, you’ll also need a handset able to tap into those networks to enjoy the speed and low latency benefits that they promise.

Lenovo-owned Motorola claims the new Moto Z3 smartphone that arrives on August 16 will be the first such 5G capable smartphone. But don’t hold your breath, there’s a catch: You’ll have to purchase a snap-on 5G “Moto Mod” accessory that won’t be available until early next year.

What's more, unless you live in one of the few early 5G rollout markets, you won't be able to exploit the blazing fast--up to 5GB per second--speeds and network responsive that will be made possible with the new technology.

The new phone will cost $20 per month for 24 months ($480) as a Verizon exclusive, with up to $300 off if you switch to the carrier and trade in an old device. No word yet on what the Moto Mod itself will cost, or what kind of fees will be charged by Verizon for a 5G data plan.

Moto Z3(Photo: Motorola)

Besides the 5G chips (from Qualcomm) and antenna inside the Moto Mod, the mod will include its own battery to help offset any battery drain on the phone itself

It also remains to be seen what Verizon’s 5G coverage area will look like by the time the Mod is made available. So far, Verizon has announced that 5G will be coming to Sacramento, Los Angeles and Houston by the end of 2018, but the initial deployments will be for so-called fixed wireless, essentially as a home-based alternative to broadband.

Rival AT&T is rolling out its own 5G networks in select U.S. cities. And T-Mobile and Sprint, which hope to get their impending merger approved by regulators, also have vast ambitions for 5G.

If 5G lives up to the hype that is building up around it, a capable handset will permit you, Moto says, to download 90 Spotify songs in 10 seconds. And 5G could supply a boost to virtual reality and numerous other technologies.

Motorola itself is banking on 5G to help restore some of the luster to a once venerable brand. Moto Mods haven’t quite take off the way Motorola presumably would have hoped, though the company says the usage stats among consumers who buy them has been steady. Earlier mods brought longer range batteries, better speakers, and even projector capabilities to Moto Z-series phones.

According to Motorola, the new 5G mod will eventually work with older Moto Z-series phones, as well, and not just the new Z3.